Apparatus for heat curing materials such as rubber compounds, plastics, etc.



June 29, 1943. c. E. BENNETT 2,323,191

APPARATUS FOR HEAT CURING MATERIALS SUCH AS RUBBER COMPOUNDS, PLASTICS, ETC Filed Dec. 26, 1940 ATTORNEYS UNITED STATES Patented June 29, 1943 APPARATUS FOR HEAT CURING MATERIALS g glc'lfl AS RUBBER COMPOUNDS, PLASTICS,

Application December 26, 1940, Serial No. 371,767

PATENT OFFICE 4 Claims.

This invention is directed to an improved method and apparatus for the continuous electrostatic vulcanization ofvulcanlzable and heat settable materials such, for example, as the insulation of compound insulated wires and cables.

One of the objects of my invention is the provision of an equipment whereby during the vulcanizing operation the material will be subjected to pressure.

The accompanying drawing shows by way of example an equipment suitable for use in the practice of my invention with respect to the vulcanizing of the insulation of wires and cables.

Referring to this drawing in detail: 2 designates a reel of bare wire.

4 designates a reel of tin strip faced with rubher or rubber compound or other vulcanizable insulating material.

6 designates equipment through which the bare wire 2 and the tin and insulating compound strip 8 are led or passed, this equipment 6 being of such a character that as the wire 2 and the composite strip 8 passtherethrough the strip 8 will be bent about the wire with the insulating compound immediately about the wire. I might say at this point that such equipment has been used in this industry prior to my invention and is familiar to those skilled in this art, which explains why this part of my apparatus has been illustrated merely diagrammatically.

The insulated wire, which I will designate ll, passes from the equipment 6 into a pressure cylinder l2. This cylinder is of metal or other suitable material sufiiciently strong to withstand high internal pressures which may be of the order of several hundred pounds per square inch.

The cylinder I2 is equipped at each end with a stufling box ll. It is to be noted that these stufllng boxes are simply a loose flt upon the insulated wire Ill.

Connected into the pressure cylinder l2, about midway of the length of the cylinder, by conduit ii, is the pressure side of a pump ii. The intake side of this pump is equipped with conduits 2| which extend away from each other and are bent upwardly to a point beneath the outer ends of the stumng boxes 14.

r The upper ends of these conduits conveniently are provided with cups 22. The conduits 20 and it as well as the pressure cylinder l2 contain oil or other fluid 24, the fluid in the cylinder l2 being maintained under pressure by the pump it.

The slight amount of oil that escapes past the stufling boxes I! which, as above mentioned, are not a tight fit on the insulated wire I0, drips into the cups 22 so as to be returned to the system and making it feasible to maintain the pressure cylinder 12 under the desired pressure at all times.

A high frequency system shown at 26 supplies the energy for the system, one side of this equipment 26 being connected to the bare wire 2, the other side to one of the stumng boxes II which, it will be understood, is of metal and contacts the tin on the insulated wire l0. As a consequence as the insulated and tin covered wire passes through the pressure cylinder l2 it will be subjected to the action of an electrostatic field to vulcanize the insulation on the wire while the insulation covering the wire is under the pressure supplied by the pressure fluid 24.

As the vulcanized assembly emerges from the far end of the pressure cylinder 12 the tin strip, which I will designate 28, is stripped therefrom and wound upon a reel 30, the wire, the insulation of which has now been vulcanized, passing forward to a suitable wind-up reel.

The high frequency equipment 26' may be mounted for convenience upon an overhead structure 32 from which it is insulated by suitable insulators The reels I and above mentioned are suspended also from this overhead structure by suitable insulators 36. I also suspend the pressure cylinder I2 along with the pump l8 and its conduits from the overhead structure 32 from which this equipment is insulated by suitable insulators 38.

It will be apparent from all of the foregoing that I have provided for the electrostatic vulcanization to take place while the material being vulcanized is enclosed in a thin metal sheath which transmits the pressure of the fluid surrounding the sheath to the insulation whereby the material being vulcanized will be held against swelling during the vulcanizing operation.

It is to be understood that changes may be made in the details of construction and arrangement of parts herein shown and described within the purview of my invention.

What I claim is:

1. An apparatus for vulcanizing the insulation of electric conductors while the insulation is enclosed in a flexible metallic sheath, said apparatus comprising in combination a pressure cylinder. a stufllng box at each end of the cylinder, means for feeding said metallic sheathed insulated conductor continuously through 'one of said stufling boxes into the pressure cylinder, through the cylinder and out through the other stuffing box,

584d boxes loosely fitting the conductor assembly, a

pump having its discharge conduit connected into the pressure cylinder, intake conduits for the pump terminating adjacent the outer ends of said stufling boxes, pressure fluid filling the pressure cylinder and said conduits, whereby as the conductor assembly passes through said cylinder its insulation will be subjected to externally applied pressure transmitted through the said metallic sheath, and means for subjecting the insulation of the conductor to the influence of an electrostatic field while under pressure, said means comprising a high frequency source of.electrical energy,;'said electric conductor being connected to one side of said high frequency source, the said metallic sheath being connected to the other side of said source.

2. In combination, means for continuously applying a layer of insulation and an outer flexible metallic layer to an electrical conductor as the,

same is drawn off a reel, a pressure cylinder through which the conductor assembly is continuously passed, a stufllng box at the entry and exit ends of the cylinder loosely fitting the conductor assembly, oil under pressure in the pressure cylinder, a pump having its discharge side connected to said cylinder for maintaining said 011 under pressure, the intake side of the pump being provided with conduits terminating at said stufling boxes for the reception of oil escaping through the stufiing boxes, a high frequency source of electrical energy having one side connected to said conductor, its other side being connected to said metallic layer whereby the conductor in sulation will be yulcanized while within the pressure cylinder and under pressure, and means beyond the exit end of the pressure cylinder for continuously stripping the metallic layer from the vulcanized insulation.

3. An apparatus for vuicanizing the insulation of electric conductors while the insulation is enclosed in'a liquid-impermeable flexible metallic sheath, said apparatus comprising in combination a pressure cylinder, a stuffing box, one of which is of metal, at each end of said pressure cylinder, means for feeding the said insulated metallic sheathed conductor continuously through one of said stufllng boxes into the pressure cylinder, through the cylinder and out through the other stufiing box, a pump having its discharge conduit connected into said pressure cylinder, liquid filling the cylinder and maintained under pressure by said pump, whereby as the conductor assembly passes through the pressure liquid in the cylinder its insulation will be subjected to the pressure of said liquid transmitted through the said liquid-impermeable flexible metallic sheath, and means for subjecting the insulation of the conductor to the influence of an electrostatic field while being so subjected to pressure, said means comprising a high frequency source of electrical energy, the conductor being electrically connected to one side of said high frequency source, and the said metallic sheath being electrically connected to the other side of said high frequency source through contact with the said metallic stumng box to-which the high frequency source is connected.

4. In combination a bare wire supply reel, a supply of tin strip faced with unvulcanized vulcanizable insulating material, means for applying the faced tin strip to the bare wire, said means lying in the path of the wire and tin strip as they are stripped from their respective reels and adapted to bend the tin strip about the wire with the insulating material immediately about the wire, a pressure cylinder in the path of the covered wire through which the wire assembly continuously passes, a liquid filling the cylinder, a pump for maintaining said liquid under pressure whereby as the assembly passes through the cylinder said tin strip will be subjected to pressure externally, this pressure being transmitted by the tin strip to the insulating material, a high insulation.

CHARLES E. BENNETT; 

